Thousands flocked to the opening day of the competition in Jakarta, paying up to USD 90 for prime seats, as the popularity of all things Japanese grows among Indonesians -- from learning the language to eating the cuisine to embracing the sports.
The two grand champions or "yokozuna", Mongolians Hakuho and Harumafuji, had been expected to dominate -- but both suffered shock defeats to lower-ranked Kisenosato.
Hakuho looked to be on impressive form as he made it through successive rounds, in one bout guiding 206-kilogrammes Gagamaru of Georgia out of the ring in seconds.
Kisenosato will now take part in the final of the two-day tournament tomorrow.
More From This Section
Before the fighting, some of the wrestlers took part in a skit which involved buttock slapping and picking up young fighters by their loincloths and hurling them around, drawing much laughter from the crowds.
"This is the first time I've seen sumo live, so it's very exciting," aikido instructor Sphinx Parlin Philips told AFP.
"This event is like an introduction to Japanese culture," added Tukuji Yoshida, from local organiser Gotanda Denshi.
The last official sumo tournament outside Japan was held in Mongolia in 2008.
Sumo is gradually emerging from a series of scandals that have tainted its centuries-old image.
Match-fixing, drug use and bullying allegations have eroded its popularity, although it still has a huge following.